Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * main.c
4 : * Stub main() routine for the postgres executable.
5 : *
6 : * This does some essential startup tasks for any incarnation of postgres
7 : * (postmaster, standalone backend, standalone bootstrap process, or a
8 : * separately exec'd child of a postmaster) and then dispatches to the
9 : * proper FooMain() routine for the incarnation.
10 : *
11 : *
12 : * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
13 : * Portions Copyright (c) 1994, Regents of the University of California
14 : *
15 : *
16 : * IDENTIFICATION
17 : * src/backend/main/main.c
18 : *
19 : *-------------------------------------------------------------------------
20 : */
21 : #include "postgres.h"
22 :
23 : #include <unistd.h>
24 :
25 : #if defined(WIN32)
26 : #include <crtdbg.h>
27 : #endif
28 :
29 : #if defined(__NetBSD__)
30 : #include <sys/param.h>
31 : #endif
32 :
33 : #include "bootstrap/bootstrap.h"
34 : #include "common/username.h"
35 : #include "miscadmin.h"
36 : #include "postmaster/postmaster.h"
37 : #include "tcop/tcopprot.h"
38 : #include "utils/help_config.h"
39 : #include "utils/memutils.h"
40 : #include "utils/pg_locale.h"
41 : #include "utils/ps_status.h"
42 :
43 :
44 : const char *progname;
45 : static bool reached_main = false;
46 :
47 : /* names of special must-be-first options for dispatching to subprograms */
48 : static const char *const DispatchOptionNames[] =
49 : {
50 : [DISPATCH_CHECK] = "check",
51 : [DISPATCH_BOOT] = "boot",
52 : [DISPATCH_FORKCHILD] = "forkchild",
53 : [DISPATCH_DESCRIBE_CONFIG] = "describe-config",
54 : [DISPATCH_SINGLE] = "single",
55 : /* DISPATCH_POSTMASTER has no name */
56 : };
57 :
58 : StaticAssertDecl(lengthof(DispatchOptionNames) == DISPATCH_POSTMASTER,
59 : "array length mismatch");
60 :
61 : static void startup_hacks(const char *progname);
62 : static void init_locale(const char *categoryname, int category, const char *locale);
63 : static void help(const char *progname);
64 : static void check_root(const char *progname);
65 :
66 :
67 : /*
68 : * Any Postgres server process begins execution here.
69 : */
70 : int
71 3664 : main(int argc, char *argv[])
72 : {
73 3664 : bool do_check_root = true;
74 3664 : DispatchOption dispatch_option = DISPATCH_POSTMASTER;
75 :
76 3664 : reached_main = true;
77 :
78 : /*
79 : * If supported on the current platform, set up a handler to be called if
80 : * the backend/postmaster crashes with a fatal signal or exception.
81 : */
82 : #if defined(WIN32)
83 : pgwin32_install_crashdump_handler();
84 : #endif
85 :
86 3664 : progname = get_progname(argv[0]);
87 :
88 : /*
89 : * Platform-specific startup hacks
90 : */
91 3664 : startup_hacks(progname);
92 :
93 : /*
94 : * Remember the physical location of the initially given argv[] array for
95 : * possible use by ps display. On some platforms, the argv[] storage must
96 : * be overwritten in order to set the process title for ps. In such cases
97 : * save_ps_display_args makes and returns a new copy of the argv[] array.
98 : *
99 : * save_ps_display_args may also move the environment strings to make
100 : * extra room. Therefore this should be done as early as possible during
101 : * startup, to avoid entanglements with code that might save a getenv()
102 : * result pointer.
103 : */
104 3664 : argv = save_ps_display_args(argc, argv);
105 :
106 : /*
107 : * Fire up essential subsystems: error and memory management
108 : *
109 : * Code after this point is allowed to use elog/ereport, though
110 : * localization of messages may not work right away, and messages won't go
111 : * anywhere but stderr until GUC settings get loaded.
112 : */
113 3664 : MyProcPid = getpid();
114 3664 : MemoryContextInit();
115 :
116 : /*
117 : * Set reference point for stack-depth checking. (There's no point in
118 : * enabling this before error reporting works.)
119 : */
120 3664 : (void) set_stack_base();
121 :
122 : /*
123 : * Set up locale information
124 : */
125 3664 : set_pglocale_pgservice(argv[0], PG_TEXTDOMAIN("postgres"));
126 :
127 : /*
128 : * In the postmaster, absorb the environment values for LC_COLLATE and
129 : * LC_CTYPE. Individual backends will change these later to settings
130 : * taken from pg_database, but the postmaster cannot do that. If we leave
131 : * these set to "C" then message localization might not work well in the
132 : * postmaster.
133 : */
134 3664 : init_locale("LC_COLLATE", LC_COLLATE, "");
135 3664 : init_locale("LC_CTYPE", LC_CTYPE, "");
136 :
137 : /*
138 : * LC_MESSAGES will get set later during GUC option processing, but we set
139 : * it here to allow startup error messages to be localized.
140 : */
141 : #ifdef LC_MESSAGES
142 3664 : init_locale("LC_MESSAGES", LC_MESSAGES, "");
143 : #endif
144 :
145 : /* We keep these set to "C" always. See pg_locale.c for explanation. */
146 3664 : init_locale("LC_MONETARY", LC_MONETARY, "C");
147 3664 : init_locale("LC_NUMERIC", LC_NUMERIC, "C");
148 3664 : init_locale("LC_TIME", LC_TIME, "C");
149 :
150 : /*
151 : * Now that we have absorbed as much as we wish to from the locale
152 : * environment, remove any LC_ALL setting, so that the environment
153 : * variables installed by pg_perm_setlocale have force.
154 : */
155 3664 : unsetenv("LC_ALL");
156 :
157 : /*
158 : * Catch standard options before doing much else, in particular before we
159 : * insist on not being root.
160 : */
161 3664 : if (argc > 1)
162 : {
163 3664 : if (strcmp(argv[1], "--help") == 0 || strcmp(argv[1], "-?") == 0)
164 : {
165 2 : help(progname);
166 2 : exit(0);
167 : }
168 3662 : if (strcmp(argv[1], "--version") == 0 || strcmp(argv[1], "-V") == 0)
169 : {
170 1494 : fputs(PG_BACKEND_VERSIONSTR, stdout);
171 1494 : exit(0);
172 : }
173 :
174 : /*
175 : * In addition to the above, we allow "--describe-config" and "-C var"
176 : * to be called by root. This is reasonably safe since these are
177 : * read-only activities. The -C case is important because pg_ctl may
178 : * try to invoke it while still holding administrator privileges on
179 : * Windows. Note that while -C can normally be in any argv position,
180 : * if you want to bypass the root check you must put it first. This
181 : * reduces the risk that we might misinterpret some other mode's -C
182 : * switch as being the postmaster/postgres one.
183 : */
184 2168 : if (strcmp(argv[1], "--describe-config") == 0)
185 0 : do_check_root = false;
186 2168 : else if (argc > 2 && strcmp(argv[1], "-C") == 0)
187 2 : do_check_root = false;
188 : }
189 :
190 : /*
191 : * Make sure we are not running as root, unless it's safe for the selected
192 : * option.
193 : */
194 2168 : if (do_check_root)
195 2166 : check_root(progname);
196 :
197 : /*
198 : * Dispatch to one of various subprograms depending on first argument.
199 : */
200 :
201 2168 : if (argc > 1 && argv[1][0] == '-' && argv[1][1] == '-')
202 466 : dispatch_option = parse_dispatch_option(&argv[1][2]);
203 :
204 2168 : switch (dispatch_option)
205 : {
206 244 : case DISPATCH_CHECK:
207 244 : BootstrapModeMain(argc, argv, true);
208 : break;
209 100 : case DISPATCH_BOOT:
210 100 : BootstrapModeMain(argc, argv, false);
211 : break;
212 0 : case DISPATCH_FORKCHILD:
213 : #ifdef EXEC_BACKEND
214 : SubPostmasterMain(argc, argv);
215 : #else
216 : Assert(false); /* should never happen */
217 : #endif
218 0 : break;
219 0 : case DISPATCH_DESCRIBE_CONFIG:
220 0 : GucInfoMain();
221 : break;
222 120 : case DISPATCH_SINGLE:
223 120 : PostgresSingleUserMain(argc, argv,
224 120 : strdup(get_user_name_or_exit(progname)));
225 : break;
226 1704 : case DISPATCH_POSTMASTER:
227 1704 : PostmasterMain(argc, argv);
228 : break;
229 : }
230 :
231 : /* the functions above should not return */
232 0 : abort();
233 : }
234 :
235 : /*
236 : * Returns the matching DispatchOption value for the given option name. If no
237 : * match is found, DISPATCH_POSTMASTER is returned.
238 : */
239 : DispatchOption
240 1980 : parse_dispatch_option(const char *name)
241 : {
242 10140 : for (int i = 0; i < lengthof(DispatchOptionNames); i++)
243 : {
244 : /*
245 : * Unlike the other dispatch options, "forkchild" takes an argument,
246 : * so we just look for the prefix for that one. For non-EXEC_BACKEND
247 : * builds, we never want to return DISPATCH_FORKCHILD, so skip over it
248 : * in that case.
249 : */
250 8624 : if (i == DISPATCH_FORKCHILD)
251 : {
252 : #ifdef EXEC_BACKEND
253 : if (strncmp(DispatchOptionNames[DISPATCH_FORKCHILD], name,
254 : strlen(DispatchOptionNames[DISPATCH_FORKCHILD])) == 0)
255 : return DISPATCH_FORKCHILD;
256 : #endif
257 1636 : continue;
258 : }
259 :
260 6988 : if (strcmp(DispatchOptionNames[i], name) == 0)
261 464 : return (DispatchOption) i;
262 : }
263 :
264 : /* no match means this is a postmaster */
265 1516 : return DISPATCH_POSTMASTER;
266 : }
267 :
268 : /*
269 : * Place platform-specific startup hacks here. This is the right
270 : * place to put code that must be executed early in the launch of any new
271 : * server process. Note that this code will NOT be executed when a backend
272 : * or sub-bootstrap process is forked, unless we are in a fork/exec
273 : * environment (ie EXEC_BACKEND is defined).
274 : *
275 : * XXX The need for code here is proof that the platform in question
276 : * is too brain-dead to provide a standard C execution environment
277 : * without help. Avoid adding more here, if you can.
278 : */
279 : static void
280 3664 : startup_hacks(const char *progname)
281 : {
282 : /*
283 : * Windows-specific execution environment hacking.
284 : */
285 : #ifdef WIN32
286 : {
287 : WSADATA wsaData;
288 : int err;
289 :
290 : /* Make output streams unbuffered by default */
291 : setvbuf(stdout, NULL, _IONBF, 0);
292 : setvbuf(stderr, NULL, _IONBF, 0);
293 :
294 : /* Prepare Winsock */
295 : err = WSAStartup(MAKEWORD(2, 2), &wsaData);
296 : if (err != 0)
297 : {
298 : write_stderr("%s: WSAStartup failed: %d\n",
299 : progname, err);
300 : exit(1);
301 : }
302 :
303 : /*
304 : * By default abort() only generates a crash-dump in *non* debug
305 : * builds. As our Assert() / ExceptionalCondition() uses abort(),
306 : * leaving the default in place would make debugging harder.
307 : *
308 : * MINGW's own C runtime doesn't have _set_abort_behavior(). When
309 : * targeting Microsoft's UCRT with mingw, it never links to the debug
310 : * version of the library and thus doesn't need the call to
311 : * _set_abort_behavior() either.
312 : */
313 : #if !defined(__MINGW32__) && !defined(__MINGW64__)
314 : _set_abort_behavior(_CALL_REPORTFAULT | _WRITE_ABORT_MSG,
315 : _CALL_REPORTFAULT | _WRITE_ABORT_MSG);
316 : #endif /* !defined(__MINGW32__) &&
317 : * !defined(__MINGW64__) */
318 :
319 : /*
320 : * SEM_FAILCRITICALERRORS causes more errors to be reported to
321 : * callers.
322 : *
323 : * We used to also specify SEM_NOGPFAULTERRORBOX, but that prevents
324 : * windows crash reporting from working. Which includes registered
325 : * just-in-time debuggers, making it unnecessarily hard to debug
326 : * problems on windows. Now we try to disable sources of popups
327 : * separately below (note that SEM_NOGPFAULTERRORBOX did not actually
328 : * prevent all sources of such popups).
329 : */
330 : SetErrorMode(SEM_FAILCRITICALERRORS);
331 :
332 : /*
333 : * Show errors on stderr instead of popup box (note this doesn't
334 : * affect errors originating in the C runtime, see below).
335 : */
336 : _set_error_mode(_OUT_TO_STDERR);
337 :
338 : /*
339 : * In DEBUG builds, errors, including assertions, C runtime errors are
340 : * reported via _CrtDbgReport. By default such errors are displayed
341 : * with a popup (even with NOGPFAULTERRORBOX), preventing forward
342 : * progress. Instead report such errors stderr (and the debugger).
343 : * This is C runtime specific and thus the above incantations aren't
344 : * sufficient to suppress these popups.
345 : */
346 : _CrtSetReportMode(_CRT_ERROR, _CRTDBG_MODE_FILE | _CRTDBG_MODE_DEBUG);
347 : _CrtSetReportFile(_CRT_ERROR, _CRTDBG_FILE_STDERR);
348 : _CrtSetReportMode(_CRT_ASSERT, _CRTDBG_MODE_FILE | _CRTDBG_MODE_DEBUG);
349 : _CrtSetReportFile(_CRT_ASSERT, _CRTDBG_FILE_STDERR);
350 : _CrtSetReportMode(_CRT_WARN, _CRTDBG_MODE_FILE | _CRTDBG_MODE_DEBUG);
351 : _CrtSetReportFile(_CRT_WARN, _CRTDBG_FILE_STDERR);
352 : }
353 : #endif /* WIN32 */
354 3664 : }
355 :
356 :
357 : /*
358 : * Make the initial permanent setting for a locale category. If that fails,
359 : * perhaps due to LC_foo=invalid in the environment, use locale C. If even
360 : * that fails, perhaps due to out-of-memory, the entire startup fails with it.
361 : * When this returns, we are guaranteed to have a setting for the given
362 : * category's environment variable.
363 : */
364 : static void
365 21984 : init_locale(const char *categoryname, int category, const char *locale)
366 : {
367 21984 : if (pg_perm_setlocale(category, locale) == NULL &&
368 0 : pg_perm_setlocale(category, "C") == NULL)
369 0 : elog(FATAL, "could not adopt \"%s\" locale nor C locale for %s",
370 : locale, categoryname);
371 21984 : }
372 :
373 :
374 :
375 : /*
376 : * Help display should match the options accepted by PostmasterMain()
377 : * and PostgresMain().
378 : *
379 : * XXX On Windows, non-ASCII localizations of these messages only display
380 : * correctly if the console output code page covers the necessary characters.
381 : * Messages emitted in write_console() do not exhibit this problem.
382 : */
383 : static void
384 2 : help(const char *progname)
385 : {
386 2 : printf(_("%s is the PostgreSQL server.\n\n"), progname);
387 2 : printf(_("Usage:\n %s [OPTION]...\n\n"), progname);
388 2 : printf(_("Options:\n"));
389 2 : printf(_(" -B NBUFFERS number of shared buffers\n"));
390 2 : printf(_(" -c NAME=VALUE set run-time parameter\n"));
391 2 : printf(_(" -C NAME print value of run-time parameter, then exit\n"));
392 2 : printf(_(" -d 1-5 debugging level\n"));
393 2 : printf(_(" -D DATADIR database directory\n"));
394 2 : printf(_(" -e use European date input format (DMY)\n"));
395 2 : printf(_(" -F turn fsync off\n"));
396 2 : printf(_(" -h HOSTNAME host name or IP address to listen on\n"));
397 2 : printf(_(" -i enable TCP/IP connections (deprecated)\n"));
398 2 : printf(_(" -k DIRECTORY Unix-domain socket location\n"));
399 : #ifdef USE_SSL
400 2 : printf(_(" -l enable SSL connections\n"));
401 : #endif
402 2 : printf(_(" -N MAX-CONNECT maximum number of allowed connections\n"));
403 2 : printf(_(" -p PORT port number to listen on\n"));
404 2 : printf(_(" -s show statistics after each query\n"));
405 2 : printf(_(" -S WORK-MEM set amount of memory for sorts (in kB)\n"));
406 2 : printf(_(" -V, --version output version information, then exit\n"));
407 2 : printf(_(" --NAME=VALUE set run-time parameter\n"));
408 2 : printf(_(" --describe-config describe configuration parameters, then exit\n"));
409 2 : printf(_(" -?, --help show this help, then exit\n"));
410 :
411 2 : printf(_("\nDeveloper options:\n"));
412 2 : printf(_(" -f s|i|o|b|t|n|m|h forbid use of some plan types\n"));
413 2 : printf(_(" -O allow system table structure changes\n"));
414 2 : printf(_(" -P disable system indexes\n"));
415 2 : printf(_(" -t pa|pl|ex show timings after each query\n"));
416 2 : printf(_(" -T send SIGABRT to all backend processes if one dies\n"));
417 2 : printf(_(" -W NUM wait NUM seconds to allow attach from a debugger\n"));
418 :
419 2 : printf(_("\nOptions for single-user mode:\n"));
420 2 : printf(_(" --single selects single-user mode (must be first argument)\n"));
421 2 : printf(_(" DBNAME database name (defaults to user name)\n"));
422 2 : printf(_(" -d 0-5 override debugging level\n"));
423 2 : printf(_(" -E echo statement before execution\n"));
424 2 : printf(_(" -j do not use newline as interactive query delimiter\n"));
425 2 : printf(_(" -r FILENAME send stdout and stderr to given file\n"));
426 :
427 2 : printf(_("\nOptions for bootstrapping mode:\n"));
428 2 : printf(_(" --boot selects bootstrapping mode (must be first argument)\n"));
429 2 : printf(_(" --check selects check mode (must be first argument)\n"));
430 2 : printf(_(" DBNAME database name (mandatory argument in bootstrapping mode)\n"));
431 2 : printf(_(" -r FILENAME send stdout and stderr to given file\n"));
432 :
433 2 : printf(_("\nPlease read the documentation for the complete list of run-time\n"
434 : "configuration settings and how to set them on the command line or in\n"
435 : "the configuration file.\n\n"
436 : "Report bugs to <%s>.\n"), PACKAGE_BUGREPORT);
437 2 : printf(_("%s home page: <%s>\n"), PACKAGE_NAME, PACKAGE_URL);
438 2 : }
439 :
440 :
441 :
442 : static void
443 2166 : check_root(const char *progname)
444 : {
445 : #ifndef WIN32
446 2166 : if (geteuid() == 0)
447 : {
448 0 : write_stderr("\"root\" execution of the PostgreSQL server is not permitted.\n"
449 : "The server must be started under an unprivileged user ID to prevent\n"
450 : "possible system security compromise. See the documentation for\n"
451 : "more information on how to properly start the server.\n");
452 0 : exit(1);
453 : }
454 :
455 : /*
456 : * Also make sure that real and effective uids are the same. Executing as
457 : * a setuid program from a root shell is a security hole, since on many
458 : * platforms a nefarious subroutine could setuid back to root if real uid
459 : * is root. (Since nobody actually uses postgres as a setuid program,
460 : * trying to actively fix this situation seems more trouble than it's
461 : * worth; we'll just expend the effort to check for it.)
462 : */
463 2166 : if (getuid() != geteuid())
464 : {
465 0 : write_stderr("%s: real and effective user IDs must match\n",
466 : progname);
467 0 : exit(1);
468 : }
469 : #else /* WIN32 */
470 : if (pgwin32_is_admin())
471 : {
472 : write_stderr("Execution of PostgreSQL by a user with administrative permissions is not\n"
473 : "permitted.\n"
474 : "The server must be started under an unprivileged user ID to prevent\n"
475 : "possible system security compromises. See the documentation for\n"
476 : "more information on how to properly start the server.\n");
477 : exit(1);
478 : }
479 : #endif /* WIN32 */
480 2166 : }
481 :
482 : /*
483 : * At least on linux, set_ps_display() breaks /proc/$pid/environ. The
484 : * sanitizer library uses /proc/$pid/environ to implement getenv() as it wants
485 : * to work independent of libc. When just using undefined and alignment
486 : * sanitizers, the sanitizer library is only initialized when the first error
487 : * occurs, by which time we've often already called set_ps_display(),
488 : * preventing the sanitizer libraries from seeing the options.
489 : *
490 : * We can work around that by defining __ubsan_default_options, a weak symbol
491 : * libsanitizer uses to get defaults from the application, and return
492 : * getenv("UBSAN_OPTIONS"). But only if main already was reached, so that we
493 : * don't end up relying on a not-yet-working getenv().
494 : *
495 : * As this function won't get called when not running a sanitizer, it doesn't
496 : * seem necessary to only compile it conditionally.
497 : */
498 : const char *__ubsan_default_options(void);
499 : const char *
500 0 : __ubsan_default_options(void)
501 : {
502 : /* don't call libc before it's guaranteed to be initialized */
503 0 : if (!reached_main)
504 0 : return "";
505 :
506 0 : return getenv("UBSAN_OPTIONS");
507 : }
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